This proposal is for a new cyclotron to support imaging research at the University of Washington. This is an exciting time for imaging in medicine with new imaging tools being developed and used to answer important questions at the cutting edge of human biology. The UW Molecular Imaging Center is a focus for collaborative and innovative research using advanced methods for non-invasive imaging of biochemical reactions in vivo. The majority of our research that will benefit from the proposed cyclotron exploits the high spatial and temporal resolution capabilities of quantitative positron emission tomography (PET). The UW PET program is 17 yrs old and is a leader in cancer and cardiac imaging research. Until now, we have purchased time on a cyclotron in the Department of Radiation Oncology. We now require a dedicated instrument to support our expanding research projects. PET imaging is being used by almost half of our medical school departments, including both basic science and clinical projects. This application describes the use of short-lived radionuclides for research projects related to cancer, the heart and brain, diabetes, and infectious diseases. Imaging using PET radionuclides is becoming a remarkably useful translational tool for UW researchers, combining laboratory, small animal, and human protocols. The proposed instrument will provide PET radionuclides with short half-lives. The Radiochemistry Group uses these radionuclides to make radiochemicals for animal research studies and radiopharmaceuticals for human studies for a wide range of well-funded NIH investigators and others who are planning projects. In order to meet our need for short-lived isotopes (18F, 11C, 13N, 15O, 94mTc, 86Y and 124I), the cyclotron will be capable of irradiating two targets at the same time and have sufficient local shielding for siting it in existing space. The CTI RDS-111 cyclotron is the instrument that best meets our research needs. Although it has the lowest energy of the cyclotrons we considered, it has high current output and relatively low shielding requirements and it will meet our current and foreseeable future needs. The space for mounting targets is modular and designed for easy mounting of custom-built targets to make radionuclides for biomedical research projects that we may not even envision at this time. This cyclotron will be a productive research tool at UW for at least 20 years, well beyond the lifetime of most high-end instrumentation.